Basic Structures of the Eye

Here is a set of notes I took about the basic structure of the eye. Enjoy! (The image is a focused shot of my right eye.

Visual process/ basic optical system - When a person looks at an object, the light rays that will reflect off the object enter the eye through the front and into the back of the eye. During the process, the light rays are bent and produce an upside-down image onto the retina. This image is then turned into electric impulses that travel to the brain where the image is translated and the object is then able to be perceived as upright. Light enters the globe through the cornea to the lens which also helps to bend the light and the light then travels through the vitreous to the retina where the information is changed into the electrical impulses and sent to the brain by the optic nerve.

Globe- the structures and membranes that together comprise the solid round shaped eyeball.

Cornea- the outermost front part of the globe. It is a thin, tough, crystal clear membrane that is sometimes called the window of the eye. It is transparent due to a lack of blood vessels which distinguishes it from other tissues as the cornea receives its nourishment from the tear film that covers its surface and a specialized fluid that flows beneath it. It provides 2/3 of the total refractive power of the eye and is the chief refracting tissue. There are five layers to the cornea body

-------- Corneal epithelium - first line of defense against injury and infection.
-------- Bowman's membrane - this membrane serves as the anchor to the epithelium layer.
-------- Corneal stroma - the main body of the cornea and contributes rigidity to the cornea. 90% of corneal thickness
-------- Descemet's membrane - provide some rigidity to the corneal body; a thin layer of collagen and elastic fibers
-------- Corneal endothelium - has cells that service pumps to maintain a proper fluid balance in the cornea and also help provide nutrients to the whole. It is a layer of delicate cells that cannot regenerate.

Sclera - the white tissue surrounding the cornea which is a strong fibrous outer layer that helps protect the intraocular parts and structures. So the white of the eye is actually bulbar conjunctiva which is translucent over the tissue of the sclera. Covers over 80% of the eyeball including whole of the rear.

Limbus - the juncture between the sclera and the cornea. The bulbar conjunctiva terminates here.

Anterior chamber - the area between the cornea and the iris. It is a small compartment filled with a fluid called aqueous humor that helps nourish the cornea. It is deepest at the center.

Iris - this structure is a colored diaphragm of tissue that is stretched across the back of the anterior chamber. In essence, creating the chamber between itself in the cornea. Using both a dilator muscle and a sphincter muscle, the iris can make the hole in the center pupil larger or smaller to control the amount of light that can be captured by the inside of the eye. It controls the pupil by involuntary reflex.

7. Pupil - this is not an actual structure; simply a name for the absence of structure or the hole in the center of the iris. The iris controls the size of the pupil and aqueous humor flows through it into the anterior chamber. It appears black because there is no light in the back of the eye to shine through to the front.

Salem and His Wonky Eye

Today was a little bit of a different day. Lately I spend most of my days resting to make sure that my foot and ankle are healing well from the surgery. I have an appointment to get my cast off in 2 weeks and I'm hopeful it will be healed up enough that I can do that and won't need to get another cast put on. So I spend my days resting and doing miscellaneous things that I can do while sitting with my foot up.

Today I realized fairly quickly that one of my cats was having a problem with his eye. Salem has chronic respiratory disease and so it is very easy for him to catch different infections due to it. I was able to make an emergency appointment with one of my local vets and get him in and he currently has drops to help his eyes feel better. If his eye doesn't feel better by Thursday, then I will have to take him back in.

The major problem today was getting him into the vet. I'm not allowed to put any weight on my foot and so finding a way to get to the shed to get the cat crate, then getting it back to the house and getting the cat into it, and then getting the box with Salem in it to the car was going to be a nearly impossible task. I did manage to get the case out of the shed and into the house while using my crutches. However, getting Salem into the box and to the car required full weight on my foot. The wonderful staff at the veterinary clinic took care of carrying him from the car and throughout the clinic as needed and then got him back to the car. Then I had to put the weight on my foot to get him back into the house.

I'm pretty sure I did not re-injure it and it doesn't feel nearly as bad as I thought it would. So yay for that! Salem looks like he's doing a little better and I'm glad I took him because he clearly needed it. However I thought it prudent to spend the rest of the day on my back with my foot up and I have done that. I'll make sure I baby the ankle more tomorrow to make sure that I take good care of it. I'm glad that it was healed up enough that I didn't hurt myself doing what needed to be done today. I'm hopeful that this will not have to happen again. I was able to make arrangements with a friend to help me on Thursday if he has to go back in to get a different antibiotic. Otherwise both of us are resting this evening and looking forward to tomorrow.

Lazy Day at Home

I've been fighting a migraine most of the day. They are always the same. Smells and light feel to strong and to bright... I feel painfully aware of them. The smell of something I would usually find pleasant now hurts and makes me wince and makes my breathing hitch because the more I smell the worse it gets. The pressure builds around my left septum and up through the left side of my head and as it feels like everything is swelling, I feel the vision fade. As the pressure builds up, I watch my vision in my left eye fade and more towards my nasal cavity ... so that looking straight ahead can make seeing anything on the left side impossible with only a little visual help from my right eye. I haven't used Relpax in awhile, but I eagerly sought it out today. In two hours I decided I needed another tablet and my vision was so screwy and the tablet so well protected in its tight sheath that I was unable to open it. I was able to have the second dose only after using scissors to try and break it out and when that failed, the small child I was watching opened it for me. (It is a bizarre testament to the strength of the packaging that nothing I could do opened it, but a six year old child with nails opened it with ease.... and yes, I showered her with gifts afterwards.)

I am so grateful that I was able to stay home today. If I had gone and had to drive back in the storm I am not sure I would have made it home safely. The opportunity to end this day sitting in the dark watching the blizzard outside from the warmth of the couch. The words 'bomb cyclone' sounded really scary... and I think it would have been if I had been out it in... but I feel safe and warm inside my home. I have so much in my thoughts right now, but I have much to be grateful for too. I hope for all to be warm and safe tonight.

Thoughts on HealthyComputing.com….

I think this site would be very useful for people who do not know a lot about computer and body ergonomics and if you are having some problems that you think are based on using your computer, check it out.... :)

I spent forty minutes looking over the site http://www.healthycomputing.com. My first inclination was to not find the site very interesting. I am having some significant health issues right now so the first section I checked out was the ‘Your Health’ section and I didn't find anything that seemed to fit me very well. I looked at all four sections and I copied out the stretches- I think that I have accidentally been doing those stretches pretty often over the last few years, but I thought I would put the copy on my fridge and remind myself about doing them more often. Under 'conditions and treatments' only one thing really was pertinent to me and has been pertinent since I was a wee child and that was myopia with slight astigmatism. I am extremely blind/ near sighted without my glasses and so it was interesting to read that my eyesight could be getting worse due to computer use. I haven’t found that it’s really getting worse over the last several years and I do use the computer a lot, but I know that my near vision should be changing soon simply due to age. When human beings reach their forties, the lens in the eye loses its ability to perform ‘accommodation’ which makes the near vision more challenging or harder to use… hence bifocals or reading glasses. Did I mention I am not looking forward to that?!?!?!

I also looked at 'Causes of Discomfort' but I didn’t see any that I tend to have troubles with over the several sections in it. I’m grateful for that! So I didn’t find this site terrible useful, but only because I have already been fairly well educated in the topic. I am determined to not need carpel tunnel surgery for as long as possible. So to sum up, I found the stretching information very interesting and printed it out for future use, but didn't find much of the rest of the information pertinent to me. :)

How about you?

“Wings” and What Not.... :D

So this week, I was able to watch most of a remastered film called “Wings”. It was a 1927 American action silent film (all words were written in borders) that starred Clara Bow, one of the great early actresses of film. The film was an original black and white, silent film w/ dramatic narration and some remastered affects that had been added (such as the orange, red plums form the back of disabled planes crashing to earth.) While this film was mostly based on war – WWII in particular, it had several aspects of the script and directing that I found interesting and worthy of analyzing and extra thought.

Clara Bow mentioned once that she felt she was put in the film because she was the studio's most popular actress and that the film didn't need her... but I will say that I loved her in the film and I'm not sure the film would have had the same 'open' flavor that I felt it had with her in it. To be blunt, I don't think it would have been at all enjoyable for me without her in it. It was her expressions and her feelings toward the character Jack Powell that actually drew me into the film and caused me to have interest in the film at all. Clara played a character called Mary Preston who found it very challenging to hide her feelings and love for Jack Powell. Jack was very attracted to another girl named Sylvia Lewis, but Sylvia is in love with a boy named David Armstrong. The boy's rivalry follows them when they both enlist in the Army to be fighter pilots and only after some tension do both David and Jack find a way to get along and become friends. The movie plot follows these two young men through the war as well as Mary Preston and how the war changed them. I highly recommend taking the time to watch it if you have the inclination.

One of the acting techniques that silent films needed to use in the past to help the viewers understand the plot of the film was to use written narration. When parts of the plot needed to move along faster, a little music and some written words could not only change the scene but also lets us as an audience know exactly how everything had changed- environment, situation, etc... In our current media, much of what we use to help move plot and emotion along is words. Films also use body language and facial expression, but words and sound really matters. Many films use sound and facial expression to help us to realize the thoughts of the characters we are watching. This film being soundless had only two options to let the audience know what was going on- the narration and the music... or the body language and facial movements. Pantomime is a wonderful skill and I felt like the written language in the film wasn't very useful to me... I felt pulled into the story through every movement on the character's faces. These actors used everything they had to express what was in their head and I felt like I could understand the words that that were said – even though I couldn't hear them- I could understand just from their faces and their eyes. Most of the emotions / thoughts that I could feel coming from the actors that helped me to understand what was going on seemed to come from directly from their eyes. At one point I found myself staring at Clara Bow and felt pulled in... sucked into her frustration and sorrow over Jack, fear for his safety and excitement over her new opportunity to drive which opens up her world a bit more. That skill- it is definitely a skill- is something that most actors these days can't (or at least don't) do. I wouldn't be at all unhappy if I found some time to finish the film outside of class. :)

So what silent films have you seen? Do you have a favorite? If you have watched this film, what did you think about it. This was my first introduction to Clara Bow and I would love to watch more things that she starred in. I felt like she was that good! Please share your thoughts... :)

2013 Poetry Corner #4 : A Sister in Sacrament Meeting

Light wavy tresses
mingling with light and dark
flowing softly, lightly down
framing her face, her eyes, her smile
head poised, listening
calmly focused, peaceful, silent
A virtuous woman before God